This invention relates to a hose clamp which is formed of a metal band provided with two looped ends. In a first embodiment of the invention the looped ends are similar and comprise an inwardly facing curved portion joined by a relatively straight portion which is bonded to the band forming a closed loop. Each loop is provided with a pair of opposed slots for receiving a threaded bolt. One of the loops retains a captive nut which cooperates with the threaded bolt to tighten the clamp when the bolt is turned. The captive nut is provided with a curved flange whose curve matches that of the curved area of the loop.
In a second embodiment of the invention one of the loops is substantially circular and houses a bushing which pivotally supports a bridging element. Because of the pivoted relationship between the bridging element and the bushing, the bridging element can adjust to a best clamping relationship around the hose as the threaded bolt is tightened.
A number of hose clamps have been invented each of which possesses one or more drawbacks which this invention overcomes. One drawback in the prior art is the excessive friction developed during the tightening process which reduces the tightening property of the clamp. Another drawback in some of the prior art devices is the lack of a tightening screw which can be quickly tensioned by means of high speed automated wrenches. Also, in some designs the nut which receives the tightening screw can become detached and lost before the clamp is placed in use. Another disadvantage of some prior art clamps is that they are very heavy in relation to their size making them difficult to use in certain applications.
In prior art clamps formed by a strip rolled over itself forming end loops with a nut and bolt acting between the loops to tighten the clamp around the hose, there remains an uncovered space on the hose between the end loops. Because of this uncovered space between the loops there is no perpendicular force acting to seal the hose in this area as the clamp is gradually closed in a radial direction against the external walls of the hose. Consequently, there is a break in the annular constraining action of the clamp which results in a pinching of the hose in this area. This pinching action raises the flexible material in the unsupported area causing a defective seal.
To avoid this negative pinching effect, there is currently a rigid extension tab or bridge, with no joint, at the bottom of one of the clamp's ends. This rigid extension tab reduces the problem described above, since it creates a bridge which exerts pressure on the space without bunching the hose between the two ends of the clamps. However, as stated above, the advance of one end of the clamp towards the other is not straight but curved, and the extension tab is rigid and not jointed, so this known tab cannot adapt precisely to the curvature of the flexible tube. This inability to adapt to the curvature of the hose in the bridging space causes wrinkles and friction damage to the hose as the clamp is tightened.
So as to avoid the problems created by a rigid extension tab, this invention provides for a tab pivotally attached to one loop end of the clamp.